function toggleView(b)
{
	var i,s,tN,hh;
	if(document.getElementById)
	{
		if(b.parentNode && b.parentNode.childNodes)
		{
			tN=b.parentNode.childNodes;
		}
		else
		{return;}
		for(i=0;i<tN.length;i++)
		{
			if(tN[i].tagName=="DIV")
			{
				s=tN[i].style.display;
				hh=(s=="")?"none":"";
				//alert("acting: "+hh);
				tN[i].style.display=hh;
			}
		}
	}
}

function reloadBlackboard()
{
	var req = null;
	try
	{
		req = new XMLHttpRequest();
	}
    catch (failed)
	{
		req = null;
	}            
	if (req == null)
		alert("Error creating request object!");
    
    //anfrage erstellen (GET, url ist localhost,
    //request ist asynchron      
    req.open("GET", 'blackboard.txt', true);
	//Beim abschliessen des request wird diese Funktion ausgeführt
	req.onreadystatechange = function()
	{
    	switch(req.readyState) 
    	{
    		case 4:
        		if(req.status!=200)
        		{
            		alert("Fehler:"+req.status); 
            	}
            	else
            	{
            		//schreibe die antwort in den div container mit der id content 
                	document.getElementById('blackboard').innerHTML = '<strong>'+req.responseText +'</strong>';
            	}
        		break;
        	default:
        		return false;
        	    break;     
		}
    };
    req.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    req.send(null);
}